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Wang S.-Y.,Qingdao University | Wang H.-L.,Taian Stomatology Hospital | Xia C.L.,Qingdao University | Ding X.,Qingdao University | And 8 more authors.
Chinese Journal of Tissue Engineering Research | Year: 2014

BACKGROUND: The adaptive reconstruction of maxillofacial muscles would happen when functional orthopedic treatment is done to cure micromaxillary deformity. The myoblast is the main responder in the process of adaptive reconstruction, and cyclic stretch can induce apoptosis of myoblasts. Caspase-9 is an important factor in the mitochondrial apoptosis pathway. OBJECTIVE: To investigate the expression of Caspase-9 in different cyclic stretch. METHODS: Based on myoblasts cultured in vitro-mechanical stimulation model, the rat L6 myoblasts were loaded stretch for 1, 6, 12 and 24 hours through multi-channel cell stress loading system, while the control group received no stretch. The morphological change and growth of myoblasts were observed under inverted phase contrast microscope; the expression of the mRNA and protein of Caspase-9 were detected by RT-PCR and western blot analysis, respectively. RESULTS AND CONCLUSION: Under inverted phase contrast microscope, the rat L6 myoblasts at cyclic stretch maintained a good growth state and biological characteristics; there was no cell degeneration; and the loss rate was extremely low, which could demonstrate that myoblast in vitro-mechanical stimulation model was established successfully. The results of RT-PCR and western blot analysis showed that, the expression of Caspase-9 mRNA and Cleaved Caspase-9 protein was significantly increased as the loading time prolonged, and the expression of Procaspase-9 protein was significantly decreased as the time. We can conclude that Caspase-9 is involved in the mechanical signal transduction of cyclic stretch. Source

Zhang Q.,Qingdao University | Wang H.-L.,Taian Stomatology Hospital | Ding X.,Qingdao University | Xia C.-L.,Qingdao University | And 10 more authors.
Chinese Journal of Tissue Engineering Research | Year: 2014

Background: Endoplasmic reticulum stress participates in the occurrence and development of many diseases, such as atherosclerosis, diabetes, and Alzheimer's disease. GRP78 is a marker of endoplasmic reticulum stress. The expression of GRP78 reflects the degree of endoplasmic reticulum stress. Objective: To investigate the effect of cyclic stretch on GRP78 expression of L6 rat myoblasts, and to identify the relationship between cyclic stretch and endoplasmic reticulum stress. Methods: In vitro culture-tensile stimulation models of myoblasts of L6 rats were established successfully. The expression of GRP78 of myoblasts exposed to cyclic stretch was determined by reverse transcription-PCR and western blot assay. Stretch groups were subjected to 15% surface elongation at a frequency of 10 cycles per minute, over a period of 1, 6, 12 and 24 hours. Cells were simultaneously seeded on a plate in the control and experimental groups with no stimulation. Results and Conclusion: The expression of GRP78 mRNA was continuously elevated over time after stretched treatment, and significant differences were detected as compared with the control group (P < 0.05). GRP78 protein expression began to increase at 1 hour after stretched treatment, was significantly increased at 6 hours, peaked at 24 hours, and significant differences were visible as compared with the control group (P< 0.05). In conclusion, cyclic stretch induced the occurrence of endoplasmic reticulum stress, which was enhanced with prolonged time. However, prolonged stretch caused severe endoplasmic reticulum stress and leaded to apoptosis of myoblasts. Source

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